From: Nicolin Chen <redacted>
Sent: Wednesday, January 8, 2025 1:10 AM

+/*
+ * Typically called in driver's threaded IRQ handler.
+ * The @type and @event_data must be defined in
include/uapi/linux/iommufd.h
+ */
+int iommufd_viommu_report_event(struct iommufd_viommu *viommu,
+				enum iommu_veventq_type type, void
*event_data,
+				size_t data_len)
+{
+	struct iommufd_veventq *veventq;
+	struct iommufd_vevent *vevent;
+	int rc = 0;
+
+	if (!viommu)
+		return -ENODEV;
+	if (WARN_ON_ONCE(!viommu->ops || !viommu->ops-

quoted

supports_veventq ||

+			 !viommu->ops->supports_veventq(type)))
+		return -EOPNOTSUPP;

Hmm the driver knows which type is supported by itself before
calling this helper. Why bother having the helper calling into
the driver again to verify?